Leap second news! A new Bulletin D from the IERS just dropped into my inbox As expected, DUT1 has increased from -0.2s to -0.1s (no link because the IERS have not updated their website yet)

A brief refresher on terminology: DUT1 is the difference between UTC (standard time from atomic clocks) and UT1 (the time judged by earth rotation) DUT1 is accurate to 0.1 second when DUT1 gets near +1 or -1, UTC gets a leap second to keep it close to UT1

oops, a correction: Bulletin D is promulgated in advance, so the actual change to DUT1 will be from the 17th July

in a week or two I expect to receive a copy of Bulletin C from the IERS, which will announce that there will be no leap second at the end of this year

normally DUT1 gets more and more negative until a positive leap second brings it back above zero things are super weird at the moment, the earth is spinning slightly faster than usual, so DUT1 is creeping UP instead of DOWN

the IERS bulletins page is iers.org/IERS/EN/Publication… but it doesn't yet have the latest Bulletin D nor (of course) the next Bulletin C

when things aren't super weird, the earth takes a little bit longer than 24*60*60 seconds to rotate, typically about 1 millisecond more, though it varies unpredictably

at the moment the earth is weirdly rotating 250 µs less than 24*60*60 seconds it is slowing down slightly, tho: last month the difference was 260 µs so the risk of an unprecedented negative leap second is slightly less